Information on the distribution, environment and biology of hatoid fishes occurring off Brazil, UNguay and Argentina is summarized and reviewed for sixty species. The Magellanie fauna is a well-defined biological unit. Conversely, the northern fauna changes gradually from the temperate Bonaerensean District off northernilrgentina, Uruguay and southern Brazil, to a subt,ropicd and tropical fauna along most of the Brazilian coast. Within the area studied, rajids are the dominant batoid family, with a large number of rhinobatids and myliobatoids to the north. An analysis (Jaccard) of distribution patterns, results in nine groups largely corresponding with biological and distributional information: Group I of Magellanic species, Group 11 of three Magellanic species extending into the Bonaerensean District, a small Group 111 formed by the deep water skates Bathyraja sehroederi, Arnblyraja [reriehsi and Dasyatis cf:pastinaca, another small Group IV of species with uncommon distributions, Group V of Bonaerensean species, GroupVI of relatively rare deep water species, Group VII of northern migrants into the Bonaerensean District, Gmup VlII of Brazilian species occurring in both the South Brazilian and Brazilian districts, and a completely different Group IX of Northcrn Brazilian species with their southern distributional limit usually at Rio de Janeiro. information is available also on depth and temperature ofoccurrence and in many cases reproduction and feeding. Preliminary evaluations of abundance have been obtained for a few species onlx but the risk of overfishing is documented for some of them. An odd taxonomicgeographic situation is the status of D, cfpaslinaca, and a peculiar type of cloaca1 gestation has been described for Be,ztlzobatis (similar to that in Squatinn). Studies at community ecology level are discussed and full references provided, including many reports only published as meeting summaries.

The demersal ichthyofauna of the continental slope of the Porcupine Seabight, eastern North Atlantic, was studied from 144 samples taken by three different types of otter trawl. At least 118 species from 43 families were represented among some 54,000 specimens collected from 247 to 2172 m soundings. Collectively, the catches were dominated in species richness by the Macrouridae, Alepocephalidae and Squalidae and in abundance by the Synaphobranchidae, Macrouridae and Moridae. Separately, relative abundance of species was more similar between the two larger trawls, setting their catches apart from the smaller net. Gear selectivity evidently accounted for this variation, which was examined by an index we developed and call species fidelity. This accounts for patterns of continuous faunal change with increased soundings concomitant with variance in species adult size and mobility. In pursuance of a more accurate representation of relative biomass and abundance than achieved hitherto, the best estimate, within the limitations imposed by the sampling gears and regime, was derived from a combination of the mean values per 200m stratum of the two large trawls with the addition of those of the eel, Synaphobranchus kaupi, from the small gear. Tentative comparisons between these results and those from elsewhere suggest that the Porcupine Seabight is generally lower in biomass and similar or lower in abundance. It was concluded that an accurate indication of ichthyofaunal structure with increased soundings can only be achieved through a detailed knowledge of the size structure of each species over its entire sounding range synthesized from a multi-trawl investigation via analyses of species fidelity.

For more than a century, two major zoogeographic provinces have been proposed for the southwestern Atlantic: a warm water Argentinean Province from Rio de Janeiro (23°S, Brazil) to Valdés Peninsula (42°S, Argentina), and a cold water Magellanic Province from Valdés Peninsula to Cape Horn. This zoogeographic scheme has been recognized so far using data covering only parts of the whole geographic area. Here, we test the validity of this scheme by analyzing the distribution of sharks, skates, rays and chimaeras, using data from research cruises covering the entire area. We used cluster, similarity and dissimilarity analyses to identify species assemblages, and canonical correspondence analysis to identify the main environmental variables affecting the composition of the assemblages. The distribution of chondrichthyan assemblages strongly supports the current zoogeographic scheme and identifies a previously unknown and distinctive deep water zoogeographic unit off southern Brazil. Both, the Argentinean and Magellanic Provinces had extensive internal structure, with four and three subareas identified in each of them, respectively. These subareas correspond, with slight differences, to previously proposed zoogeographical districts within the Argentinean Province and confirm ecological differences within the Magellanic Province. Species composition had the highest correlation with depth and bottom water temperature. Since the distribution of anthropogenic disturbances in the region is uneven, different assemblages can be subjected to different impacts. Our results provide an objective basis to establish priority areas for the conservation of chondrichthyans in the southwestern Atlantic.

No abstract

Thirty-four tows of an 8-6-m wing-end spread semi-balloon trawl made between 2230 and 4787 m in the Porcupine Seabight and Abyssal Plain (eastern North Atlantic) were used to investigate demersal ichthyofaunal ecology. The catches yielded almost 3800 specimens, representing 15 families and 43 species. In species richness the families were dominated by the Alepocephalidae and Macrouridae, in abundance by the Macrouridae and Moridae. Restricted sounding ranges of varying width produced different trends in species first and last occurrence with increased soundings. Evidence of improved sampling efficiency below 2200 m soundings suggested that relative abundance and biomass estimates of this trawl are more reliable than at shallower soundings. Tentative comparisons in abundance and biomass with samples from other regions indicated that the Porcupine area yielded similar or slightly lower values. The so-called 'bigger-deeper' trend (Heincke's Law) was examined from upper slope to abyss. It was shown to be a sampling artefact arising from avoidance of small trawls by large specimens at mid-and upper-slope soundings. At specific level, however, a 'smaller-shallower' trend was confirmed among several species.

Rays are among the largest fishes and evolved from shark-like ancestors nearly 200 million years ago. They share with sharks many life history traits: all species are carnivores or scavengers; all reproduce by internal fertilisation; and all have similar morphological and anatomical characteristics, such as skeletons built of cartilage. Rays of the World is the first complete pictorial atlas of the world’s ray fauna and includes information on many species only recently discovered by scientists while undertaking research for the book. It includes all 26 families and 633 valid named species of rays, but additional undescribed species exist for many groups. Rays of the World features a unique collection of paintings of all living species by Australian natural history artist Lindsay Marshall, compiled as part of a multinational research initiative, the Chondrichthyan Tree of Life Project. Images sourced from around the planet were used by the artist to illustrate the fauna. This comprehensive overview of the world’s ray fauna summarises information such as general identifying features and distributional information about these iconic, but surprisingly poorly known, fishes. It will enable readers to gain a better understanding of the rich diversity of rays and promote wider public interest in the group. Rays of the World is an ideal reference for a wide range of readers, including conservationists, fishery managers, scientists, fishers, divers, students and book collectors.

A new species of electric ray of the genus Torpedo is described from the eastern Gulf of Aden, northwestern Indian Ocean. Torpedo adenensis, n. sp., is placed in the subgenus Torpedo due to the presence of small, knoblike papillae around its spiracles. It is distinguished from all other congeners by its unique dorsal coloration, consisting of a uniform reddish-, rusty-, or orange-brown without any distinctive spots, blotches, or reticulations. A unique combination of characters further distinguishes T. adenensis, including the proximity of the spiracles and eyes, the distance between the second dorsal and caudal fin, which is greater than the distance between the first and second dorsal fins, and the presence of an integumental flap in the clasper glans region. Torpedo adenensis is sexually mature when between 280 and 395 mm in total length, is known from specimens of both sexes, including adults and subadults, and is the only species of Torpedo unequivocally reported from the Gulf of Aden to date.

No abstract